1. Field of the Invention
The present invention relates to a method for forming a diaphragm from brittle material, for example, used in a loudspeaker device.
2. Prior Art
A hot press method or a hot isostatic press method is known for shaping metal plates.
However, these methods are used for metals having a high ductility, and are not applicable for shaping brittle metals such as berylium, which is suitable for diaphragms of high tone speakers. Therefore, a deposition method or a powder metallurgy method, must be adapted to form a metal plate from highly brittle materials, which has less productivity efficiency.
On the other hand, berylium has a small internal energy loss, therefore a diaphragm made of berylium has a strong peak of reasonance at a high frequency range. A diaphragm of ceramics such as Al.sub.2 O.sub.3 or SiC, which is made by a moulding process, is inferior in efficiency of reproduction (regeneration) of sound because of its high density.
An object of the present invention is, therefore, to present a method of forming a diaphragm from a plate of highly brittle materials.
Another object of the present invention is to present a diaphragm having a higher performance than a conventional one.